Have tooth on top in back had root canal 10 yrs.it kills me at night.xrays show nothing. posted similar question but notice its that 1 tooth.any ideas?

See an endodontist: Oral pain such as certain toothaches or cracked / fractured teeth can often be difficult to diagnose. In addition to dental school, endodontists receive 2-3 more years of advanced education in this kind of diagnosis and treatment. That’s why you should see an endodontist for proper diagnosis and treatment.

Root Canals can fail: Upper molars have great variation in their nerve canal structure. It can be difficult to find all the canals in order to properly clean and fill them. If a canal is missed during the original root canal, it can become painful and infected later - sometimes many years later. Another possible cause could be a crack in the root. Your dentist will do tests to determine the cause.

RCT failure: Can happen due to infection ,or microscopic fracture both not visible in X-ray . Have a consultation with an endodontist to see if re treatment is even an option ,or extraction and replacement with a bridge or an implant?